1. Field of the Invention
This invention relates to an apparatus for automatically applying top end stops to a slide fastener chain.
2. Prior Art
In the manufacture of slide fasteners, it is the conventional practice to provide a fastener chain consisting of a pair of stringer tapes each having spaced groups of interlocking fastener elements along the inner edges thereof with the opposed fastener elements on the respective tapes interengaged. Each group of the fastener elements is spaced from adjacent groups by a blank tape portion devoid of any fastener element. Each group designates the length of an individual fastener to be produced. Before the chain is cut at the blank portions to provide individual fasteners, it is desirable to subject the chain to various fastener assembling operations such as mounting of top and bottom end stops and sliders.
The present inventor has proposed a method and apparatus for applying top end stops to a slide fastener chain while the latter is being advanced in a continuous flow, as disclosed in U.S. Pat. No. 3,689,980. While this prior-art apparatus has many advantages including mounting of top end stops on a fastener chain at increased rate of speed, it has encountered with a difficulty in that since the mounting of top end stops is effected with the feed roller held in intimate engagement with its associated pressure roller, the leading fastener element on either of two opposed stringer tapes is prone to receive excess or greater pressure in abutting engagement with a top stop clamping means than the leading fastener element on the other stringer tape due to the fact that either of the two opposed leading elements is positioned normally one element pitch or sometimes even longer distance out of registration with the other. This would result in misaligned fastener elements. In order to eliminate such difficulty, the various operating parts of the apparatus have been required to be adjusted in their operation timing, involving highly skilled manipulation and considerable time consumption.